Without limiting the scope of the invention, its background is described in connection with treatment of hypertension and other chronic medical conditions including but not limited to peripheral arterial disease (PAD), Raynaud's syndrome, coronary heart disease (CHD), coronary artery disease (CAD), diabetes, pulmonary hypertension (PH), and connective tissue disorders.
By definition, chronic conditions are present when there is a persistent or lasting medical problem. For example, hypertension is considered to be present when there is persistent elevation of either systolic blood pressure or diastolic blood pressure, or when a patient has been placed on antihypertensive medication because of persistently elevated blood pressure (regardless of the current blood pressure level). The blood pressure level correlates directly with the magnitude of risk for clinical sequelae such as premature death, stroke, myocardial infarction, congestive heart failure, renal insufficiency, dementia, and peripheral vascular disease. As a result, numerous antihypertensive drugs have been developed to treat elevated blood pressure. Well known classes of prevalent anti-hypertensives include Angiotensin-Converting Enzyme (ACE) Inhibitors, Alpha1 Antagonists, Angiotensin II (AT1) Receptor Antagonists, β-Blockers, Calcium Antagonists, Central Adrenergic Inhibitors, Direct Vasodilators, and Diuretics.
Pharmacological blood pressure lowering reduces the risk of premature cardiovascular morbid and fatal events as well as all-cause mortality. Antihypertensive drug therapy has also been shown to prevent the gradual progression of mild hypertension to more severe elevations of blood pressure. The prevalence of pressure-related target-organ damage (i.e., elevated serum creatinine, left ventricular hypertrophy) is also greater at higher blood pressure levels. Hypertensives (individuals with chronic hypertension) with pressure-related target-organ damage manifest a several-fold higher risk for pressure-related clinical complications at a given blood pressure level compared to hypertensives with similar levels of pressure without target-organ damage. Early treatment of hypertension favorably impacts long-term clinical risk, in part, by preventing the development of pressure-related target organ damage. However, hypertensive agents can cause hazardous side effects related to the dosage of medicine, the dangers of a rapidly decreasing blood pressure, and ischemic infarction of organ tissues (e.g. angina pectoris, myocardial infarction, transient ischemic attack, and stroke).
Similarly, other chronic conditions such as peripheral arterial disease and diabetes are also treated by pharmacological therapies. Several other important therapeutic principles are considered in treating patients of chronic conditions. In most cases, there is minimal to no value in rapid pharmacological control of a persistent or recurring condition. Rather, the goal for the vast majority is to prescribe a combination of appropriate lifestyle modifications (e.g. weight loss, dietary restriction, and increased physical activity) plus the lowest doses of drug(s) that allow for normalization over the long term. Further, many medications have dose-related side effects. Drug acquisition costs also usually increase at higher dose levels. In certain instances, cost is a major barrier to patient compliance with prescribed drug therapies. However, even the other noninvasive lifestyle approaches to chronic disease management can be tempered with side effects and ineffectiveness. For example, regular exercise is known to lower blood pressure in healthy individuals by inducing ischemia but also is problematic because it causes an increase in heart rate that may not be tolerated well by some individuals. Further, exercise, diet, and weight loss programs are all well known to suffer problems of compliance.
Accordingly, what are needed are further methods and apparatus for the management and treatment of chronic medical conditions, in particular hypertension, as well as methods and apparatus for applying ischemic conditioning to improved athletic performance.